<%@page pageEncoding="UTF-8"%>
<html>
<head>
    <meta charset="UTF-8">
</head>
<body>
<h2>Hello World!</h2>

<form action="/cal" method="post">
    <input type="text" placeholder="请输入操作数" name="a"/>
    <select name="op">
        <option selected = "selected" disabled >请选择操作符</option>
        <option>+</option>
        <option>-</option>
        <option>*</option>
        <option>/</option>
    </select>
    <input type="text" placeholder="请输入另外一个操作数" name="b"/>
    <input type="submit" value="提交"/>
</form>

</body>
</html>
